Creating a stack

We are going to create our own class to represent a stack. Let's start from the basics and declare our class:

function Stack() {
    //properties and methods go here
}

First, we need a data structure that will store the elements of the stack. We can use an array to do this:

var items = [];

Next, we need to declare the methods available for our stack:

• push(element(s)): This adds a new item (or several items) to the top of the stack.
• pop(): This removes the top item from the stack. It also returns the removed element.
• peek(): This returns the top element from the stack. The stack is not modified (it does not remove the element; it only returns the element for information purposes).
• isEmpty(): This returns true if the stack does not contain any elements and false if the size of the stack is bigger than 0.
• clear(): This removes all the elements of the stack.
• size(): This returns how many elements the stack contains. It is similar to the length property of an array.

The first method...